This invention relates to encapsulations for semiconductor integrated circuit chips and more particularly to molded plastic encapsulations using lead frames for interconnecting means.
Semiconductor chips are encapsulated both for protection, and for convenience in interconnecting the chip circuits with terminals on mounting media such as printed circuit boards. Encapsulation also facilitates testing and the automatic assembly of chips into apparatus. There is a considerable variety of integrated circuit chip packages, but of chief interest are the nonhermetic, post-molded plastic types known as the dual-in-line package and the chip carrier type. Standard exist or are under development for packages of these types which prescribe general dimensions, types of external contacts, and contact spacing.
However, the encapsulation of semiconductor devices constitutes a considerable proportion of the total cost of a completed device. Accordingly, there is a continuing effort to develop packages and encapsulation techniques which reduce cost, provide high reliability, and which are compact in size. Automatic fabrication, test, and assembly techniques contribute to lower cost and higher reliability. It is desirable also, that a particular package design accommodate, with little or no change in that design, a variety of different semiconductor chips. As a consequence, the total number of package sizes required for all chip sizes is minimized.
Accordingly, an object of this invention is a package design which can be readily adapted to different semiconductor chip sizes and configurations by relatively simple modifications.
Another object is a package design consistent with a high degree of automation from initial fabrication through test procedures and final assembly. Ancillary to this object is a design consistent with reel-to-reel processing using beam tape.
A further object is a package design adapted for handling in linear magazines, generally known as sticks, thereby enabling a high degree of automation in testing, aging, shipping, and other post-fabrication operations.
A further object is a package design adapted to provide an external electrical backside contact, as well as heat dissipation by conduction into the mounting substrate by convection from an extended backside surface.
Another object is a package design having a minimum number of lead contacts between chip contact and the contact external to the package. Ancillary to this object is a lead design contributing to superior electrical performance.
Another object is a package design which is compact in size.